CVE-2026-34457Network attack vector

Pre-authentication access via health-check User-Agent spoofing

Published Apr 14, 2026 · Updated Apr 14, 2026

Authentication bypass in OAuth2 Proxy before 7.15.2 allows remote attackers to access protected upstream resources with a spoofed User-Agent. The health-check handler accepts the configured probe User-Agent on every request path and returns success before normal authentication. In auth_request-style deployments, the bypass requires --ping-user-agent or --gcp-healthchecks and exposes upstream data and actions.

CVSS severity9.1
Critical
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in OAuth2 Proxy before 7.15.2 allows remote attackers to access protected upstream resources with a spoofed User-Agent. The health-check handler accepts the configured probe User-Agent on every request path and returns success before normal authentication. In auth_request-style deployments, the bypass requires --ping-user-agent or --gcp-healthchecks and exposes upstream data and actions.

The record

CVE
CVE-2026-34457
Published
Apr 14, 2026
Updated
Apr 14, 2026
Vendor
OAuth2 Proxy
Product
OAuth2 Proxy
Classifications
CWE-290, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 7.15.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OAuth2 Proxy · OAuth2 Proxyversion=< 7.15.2

Published CVSS scores

9.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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